This invention relates to a hermetically sealed reciprocating compressor and in particular to an arrangement whereby lubricating oil entrained within the refrigerant discharge gas is separated therefrom prior to the mixtures's exit through a discharge tube from the shell of the hermetically sealed compressor.
It has been found that significant increases in energy efficiency may be achieved in a hermetically sealed reciprocating compressor by eliminating the use of the suction gas to cool the motor windings prior to its entry into the compressor's cylinders. The superheating of the suction gas resulting from its use to cool the motor windings increases the amount of energy used by the compressor in compressing the refrigerant gas. Accordingly, it is desirable to utilize the discharge gas in lieu of the suction gas to achieve motor cooling and to prevent any heat transfer from the discharge gas to the suction gas.
One of the problems encountered in compressors utilizing discharge gas for motor cooling is the carry-over or entrainment of lubricating oil in the discharge gas. The entrained hot oil superheats the refrigerant gas and accumulates in the condenser and evaporator coils, reducing the capacity of the coil to transfer heat and reducing the mass flow rate of refrigerant through the coils. Both of the foregoing results of oil carry-over are adverse factors relative to energy efficiency of a refrigeration unit.
Heretofore, rotary compressors of various designs have employed discharge gas to cool the motor windings. It has been the common practice to use a rotating element, as for example a rotor plate attached to the motor's rotor or shaft, to achieve oil and refrigerant gas separation. Alternatively, baffle members have been employed to achieve separation. In either case, use has been made of the physical characteristic that refrigerant gas is relatively lighter than lubricating oil to achieve separation.
The present invention relates specifically to a hermetically sealed reciprocating compressor wherein separation of lubricating oil from the discharge gas is achieved without requiring the use of additional elements such as rotating plates or baffles.